Chickens stand as sentinels in Mobile’s battle against mosquito-borne illnesses

Blood tests on hens can indicate early signs of devastating illnesses

Mobile County Health Officer Dr. Kevin Michaels holds one of the sentinel chickens, just before it is sent to the field to guard county residents against mosquito-borne illness. Photo by Dan Anderson.

Relying on 100 hens as the first line of defense against a host of devastating viruses may sound vaguely comical. But it’s no joke.

Raised from tiny chicks, they are fed, watered and looked after at the Mobile County Health Department for several months. As the weather warms into Mobile’s steamy summer, the full-grown hens are sent by foursomes to coops around the county, from Citronelle to Dauphin Island, from the Mississippi border to the shores of Mobile Bay.

Blood tests on those hens trigger an early warning of mosquito-borne illness — ones you hope to avoid, like West Nile virus, eastern equine encephalitis and St. Louis encephalitis. Additional tests, done at the University of South Alabama, now also identify Zika, dengue and chikungunya.

When those tests sound an alarm, the Health Department responds by upping its mosquito control program.

This is a battle that has been raging for some 200 years.

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Back in 1819, the year Alabama became a state, Mobile was hit by a yellow fever outbreak — losing some 430 out of about 1,000 residents. That’s 40% of the population.

The Mobile County Health Department, formed even before statehood in 1816, was created to deal with just that problem.

Today, the disease control efforts are led by the county health officer, Dr. Kevin Michaels, and Derrick Scott, director of the Bureau of Environmental Health — the unit of the health department that’s responsible for vector control. Vectors are insects, rodents and other animals that can harbor diseases and spread them to humans.

While Michaels’ and Scott’s names may not be household words around Mobile, when they start talking about mosquito control, the names they mention are hallmarks of health care history — Dr. Carlos Finlay, who first speculated that mosquitos might be the culprits in the yellow fever spread; Dr. Walter Reed, who proved it; and Toulminville native Dr. William Gorgas, who at first disbelieved, but after seeing the scientific evidence became not only a believer but also a leader in efforts to control mosquitoes.

The handsome Mobile County Health Department building at St. Anthony and Bayou streets bears Gorgas’ name over the clinic entrance.

And the work of the three men, nearly two centuries ago, enabled not only the building of the Panama Canal but healthy human habitation in Mobile.

No one knows for certain where that early yellow fever epidemic originated, Michaels says, but it was reported in the early 1700s, when the French had established trade through the port. A camp for fever victims was established upriver at Fort Stoddert, in what today is the town of Mount Vernon.

But until Reed’s research at the Panama Canal, no one could figure out how to stop the spread. After the work of Reed and Gorgas, serious efforts were launched in Mobile to drain swampy areas and control mosquitos.

The last major yellow fever outbreak in Mobile was way back in 1905.

“We don’t have yellow fever, but it’s always a concern,” says Michaels.

The Zika virus epidemic in the last decade moved from travelers to mosquitos and back from Africa and South America to the Pacific islands and the U.S., mutating as it traveled. “Viruses just look for a host,” says MCHD public information officer Mark Bryant.

Hence the chickens.

“Think about the life cycle of the mosquito. It bites me” — slapping his arm — “and I kill it, that’s it,” said Michaels. “It’s over and done with.”

But if a mosquito takes her blood meal from an infected human, she may well transmit the infection to her larvae. And most of the larvae will be infected.

Finding the water to breed is a piece of cake. The water in the cap of a plastic water bottle is plenty for her egg-laying purposes. So, a major part of mosquito control is clearing the trash that can hold water.

Trucks are dispatched around the county all summer, spraying pesticides as needed. Off-road vehicles help reach more remote areas, and a plane handles the salt marshes in the south part of the county. In total, about 1,000 spraying missions are sent out each summer to cover Mobile County’s 1 million acres.

And fish that feast on mosquito larvae are introduced to ponds throughout the county.

Health officials keep a wary eye for any positive blood tests among the chickens, also checking mosquitos caught in a series of traps around the area. And on the rare occasions when a human is infected, officials look for any overlap between the sites.

Mosquito control efforts are escalated in any affected region of the county.

“Everybody thinks of pest management as spraying and killing,” Michaels says. “People get concerned about spraying. What does the pesticide do in the community? We use safe pesticides — if applied appropriately, they should provide no harm to people, to pets, to foods or to bees.” And the health department is required to apply them appropriately.

Oh, and one more way the chickens help. Chickens don’t just get bit by mosquitos — they eat them, too.

Since the chickens aren’t harmed by the viruses, they and their eggs are distributed to county residents.

Individuals can protect themselves in many other common-sense ways, rather than doing additional spraying in their own backyards, Michaels says.

For example, keep your yard free of any standing water; wear light-colored, long-sleeved clothing to keep mosquitos away; use a DEET skin repellent; apply permethrin to clothing if you’ll be out when mosquitos are active; and, if possible, avoid peak biting times — early morning and early evening, typically.

It works, Michaels notes. Some 420,000 people live in Mobile County and typically only two or three a year are diagnosed with these arbovirus illnesses. And those people may have picked up the disease not from a Mobile County mosquito but while travelling in another part of the world.

“It’s not a big threat,” says Michaels, “but it’s a threat that we have to take seriously; because we don’t want what happened in 1700s, when colonial trade brought in illness.” When we import illness, he says, it takes a while to bring it under control.

And while most people overcome even these difficult illnesses, some people don’t and some suffer long-term disabilities.

When mosquitos and the viruses they carry are under control, it’s a boon to the community, he notes. People feel comfortable going to a concert in the park or a gathering with friends or other outdoor events. They get more exercise, they probably buy something at a store or restaurant, cycling more life through the community.

But the bottom line is a simple truth of public health.

“It’s awful when a person becomes ill and ends up in the hospital with something we shouldn’t have in our community,” Michaels says.

Nedra Bloom is a writer/editor for Business Alabama and Dan Anderson is a freelance contributor. Both are based in Mobile.

This article appears in the July 2023 issue of Business Alabama.

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